Electric furnace.



ZQL' in 65565 C. A.'PFANSTIEHL.

ELECTRIC FURNACE. APPLICATION FILED JULY ll, I914.

Patented Feb. 27, 1917.

a By C lziffansijz'kl zim vi .GARL A. PI'F'ANSTIEHL, or

WAUKEGAN, ILLINOIS, ASSIGNOR T0 PFANSTIEHL COMPANY,

A CORPORATION OF DELAWARE.

ELECTRIC FURNACE.

Specification of Letters Patent Patented Feb. 27, 1917.

Application filed July 11, 1914. Serial No. 850,349.

To all whom it may concern:

Be it known that I, CARL A. PrAN TIEHL, a citizen of the United States, resii ing at \Vaukegan, in the county of Lake and State of Illinois, have. invented certain new and useful Improvements in Electric Furnaces, of which the following is a full, clear, concise, and exact description.

My invention relates to electric furnaces and particularly to electric furnaces or the 'class adaptable for use in metallurgicaloperations such as welding, fusing, and the heat treatment of metals, etc.

' The specific form of my invention herein shown and described is primarily intended for welding disks of tungsten to the heads of steel or iron tacks, rivets or screws.

My invention is fully set forth in the de scription and illustrated in the accompanying drawings,'in which-- Figure 1 is a longitudinal sectional view of the furnace, the electrical connections being diagrammatically illustrated;

Fig. 2 is a fragmentary elevational view of the left end of the furnace shown in Fig. 1;

Fig. 3 is a fragmentary elevational view illustrating one end of the heating element andhWater-cooled terminal associated therewit h Fig. 4 is a top plan view of one of the boats or trays for supporting contacts to be subjected to the heat produced within the heating chamber of the furnace; and

Fig. 5 is'an elevational View of a contact, for the treatment of which niy electrical furnace is primarily intended.

Similar numerals refer to similar parts throughout the several views.

Referring first to Flg. 1, 1t will be seen that the furnace comprises an iron vessel 10, through which passes a steel tube 11. The tube 11 extends a considerable distance beyond the right end of the vessel 10 and is provided with a surrounding shell 12, ar-

ranged to contain a jacket of cooling water.

The cooling water is supplied to the shell 12' through suitable tubes 13 and 14, as illustrated. Disposed within the steel tube 11 .and spaced therefrom, as illustrated, is an alundum tube 15. The tube 15 is therefore refractory and heat-resisting and is more or less porous. The shell 10 is preferably .the passage 19 to cool the terminals.

filled with powdered calcium oXid, Which serves as a heat insulator to retain the heat within the heating zone of the furnace.

Disposed within the alundum tube 15 is a heating element 16 of semi-circular crosssection and preferably made of carbon or graphite. The ends of the semi-circular heating element are reduced at 17 17, and fixed upon the reduced ends of the heating element are the bifurcated ends of brass or copper terminals 18, 18. Each of the terminals 18 is provided with a substantially U-shaped channel 19, each of the legs of which communicates with a pipe connection 20, whereby water may be circulated through he terminals 18, 18 are arranged to be connected with a suitable source of current.

In the drawings I'have illustrated a generator at 20, a rheostat 20 and a transformer 20. I wish it to be understood, however, that the particular source of current is immaterial, it being only necessary that the terminals 18, 18 be connected with a source of current capable of supplying sufficient energy to heat the element 16 to the required temperature. Thecarbon heating element 16 is provided near its ends with notches 21, 21, in order to cause an absolutely equalized distribution of heat throughout the heating zone of the carbon heating element. It will be seen that due to the presence of the notches 21, 21, the resistance of the heating element is materially increased near its ends and thus equalized distribution of heat is made possible. In order to prevent the oxidization of the constituent elements of the contact whilethey are being subjected to the heat produced withinthe'furnace, the space between the steel tube 11 and the alundum tube 15 communicates with a small pipe 22 passing through the steel shell 10. The pipe 22 is designed to be connected with a source of absolutely dry and substantially chemically pure hydrogen. Due to the porosity of the alundum tube the hydrogen seeps therethrough and passes into the heating chamber formed by the alundum tube. An atmosphere of hydrogen is thus maintained within the heating chamber and the oxidization of the contact parts is avoided.

At 23 in Fig. .4 I have illustrated a tray rod of silica.

of refractory arranged to carry a plurality of contacts 24:, one ofwhich is illustrated in detail in Fig. 5. Each of the contacts referred to comprises a disk 25 of tungsten, a base metal backing 26 and a thinfihn or disk 27 of copper or other suitable material interposed between the tungsten disk 25 and base metal backing 26. The elements of the contact are assembled and placed in the tray 23. When the contacts are treated in the heating chamber of the electric furnace the disks .2? fuse and thus effectually join the tungsten disks 2:) to their associated base metal backings 9.6.

In operation, the base metal backings, tungsten disks and copper disks are arranged as indicated in Fig. 5, and are placed in trays of thetype shown in Fig. 4:. The trays are then placed upon the upper surface of the semi-circular carbon heating element 16 and are pushed into the furnace chamber from the left-hand end thereof. The trays and contacts supported thereby are permitted to rest within the heating zone for a period of twenty or thirty seconds. They are then pushed on through the cooling zone of the furnace; that is, that portion of the alundum tube surrounded by the water jacket. The trays supporting the contacts are pushed through the furnace chamber by hand and by means of a long The hydrogen which percolates through the alundum tube into the heating chamber flows out of the ends of the alundum tube, where it may be lighted and burn or where it may be permitted to escape into the atmosphere. The terminals of the furnace illustrated in the present application are preferably supplied with a current of 500 or (300 amperes, alternating or direct, the current serving to heat the central part of the carboirheating element to a white heat, the exact temperature being regulated by a rheostat in the main circuit. l[ find that although the contacts are subjected to intense heat Within the heating zone, they are quite cool after having been passed through the cooling zoue and may be picked up in the hand as they emerge from the right hand end of the furnace chamber.

Having thus described my intention, what ll claim as new and desire to secure by Letters Patent of the United States is:

1. An electric furnace comprising a tube porous material, a shell around said tube forming an annular chamber, ineansfor supplying said annular chamber with hydrogen, a carbon heating element of semi-circular cross-section disposed within the said tube, and conducting means connecting the opposite ends of said heating element with a source of current whereby'it is heated by the current passing through it.

2. An electric furnace comprising, in combination, a tube of refractory, porous, heatnarrate? formin an annular s )ace between the tube and shell, means for supplying said annu-- lar space with hydrogen, a heating element disposed within the tube ar 'anged to support articles to be treated, and conducting means connecting the ends of said heating element with a source of current for heating it and the articles supported thereon.

3. An electric furnace comprising, in combination, an alundum tube, a steel shell surrounding said alundum tube, means for admitting lrrdrogeu to the space between the tube and shell, a carbon resistance element of semi-circular cross-section disposed within the alundum tube, terminals associated with the ends of said heating element, channels in said terminals arranged to have cooling water passed therethrough, and y conducting means connecting said terminals with a source of current whereby the carbon resistance element is heated.

r. An electric furnace comprising, in combination, a tube of refractory porous malerial forming a heating chamber, a shell forming an annular space around said tube, means for supplying hydrogen to said space whereby the hydrogen may percolate through the tube into the heating chamber, a resistance element of substantially semicircular cross-section disposed within the heatingchamber and arranged to support articles to be treated in the heating chamber, and means connecting the ends of said resistance element with a source of current whereby it and the articles supported thereon are heated.

5. An electric furnace comprising a receptacle arranged to contain heat-insulating material, a shell disposed in said receptacle and embedded in the heat-insulating material, a tube of refractory porous material disposed in said shell and spaced therefrom, means for supplying hydrogen to the space bet ween the tube and shell, and a resistance element within said tube for heating it.

6. An electric furnace comprising a long and slender tube of refractory material forming a resistance chamber, a heating element of substantially semi-circular. crosssection disposed in said heating chamber to form the floor thereof and arranged to support articles to be treated within the heating chamber, and m ians one at each end of the tube connecting the ends of said resistance element with a source of current to heat it and the articles thereon.

7. An electric furnace comprising, in combination, a long and slender tube of refractory material forming a heating chamber, a work supporting resistance element disposed in the heating chamber and forming the floor thereof, means connecting the ends of said resistance element with a source of current, and restrictions in said resistance elelnent to cause an equalized distribution of heat throughout the heating zone of the furnace.

8. An electric furnace comprising, in combination, a tube of refractory material forming a furnace chamber, a heating element in the furnace chamber, heat-insulating material surrounding the heating zone of the furnace outside the refractory tube, restrictions in the heating element near the ends of the heating zone to cause an equalized distribution of heat Within the heating zone, and a water jacket surrounding said tube on one side of the heating zone whereby articles subjected to the heat created within the heating zone of the furnace chamber may be 'cooled before they are passed from the furnace chamber.

9. An electric furnace comprising, in combination, a tube of refractory material forming a heating chamber, a resistance element disposed within the heating chamber and forming the floor thereof, said resistance element arranged to support articles to be treated within the heating chamber, means for connecting the ends of said resistance element with a source of current, and notches in said resistance element adjacent its ends to cause an equalized distri-' bution of heat within the heating zone of the furnace.

10. An electric furnace comprising, in combination, a receptacle arranged to contain a supply of heat-insulating material, a steel tube extending through said receptacle and projecting beyond one end thereof, an alundum tube disposed within said steel tube and spaced therefrom, means for supplying hydrogen to the space between the steel tube and the alundum tube, whereby hydrogen may percolate through the alundum tube to the interior thereof, a water jacket surrounding that portion of the steel tube projecting from the receptacle, a heating element having a substantially semicircular cross-section disposed within the alundum tube and arranged to support articles to be treated, terminals for said heating element, passages in said terminals through which cooling water may be passed, and notches in the heating element adjacent the ends of said receptacle to cause an equal distribution of heat within the heating zone of the chamber formed by the alundum tube.

In witness whereof, I hereunto subscribe my name this 8th day of July, A. D. 1914.

CARL A. PFANSTIEHL.

\Vitnesses ALBIN E. AHLBERG, Many A. CooK. 

